The present invention relates to a compressor which compresses gas supplied, for example, to a fuel cell.
Japanese Unexamined Patent Publication No. 2002-295386 discloses a compressor having a gas cooler in which discharge gas discharged from compression chambers is cooled in order to protect piping provided downstream of the compressor against heat (See pages 3 to 5 and FIG. 1 of the reference). The compressor of the above reference is a scroll type compressor which is provided with a back cooling chamber at the back of a fixed scroll member of the compressor. The gas cooler in which the discharge gas flows is disposed so as to adjoin the back cooling chamber. The gas cooler is constructed specifically such that both of gas in the compression chambers and the discharge gas in the gas cooler are cooled by cooling water that serves as cooling medium which flows in the back cooling chamber.
In the above reference, however, since the cooling water in the back cooling chamber is heated by heat of the discharge gas, the gas in the compression chambers tends to be hard to be cooled, so that there has been a fear that the efficiency of cooling the discharge gas is reduced. In addition, there has been another fear that the gas in the compression chambers is not cooled sufficiently by the cooling water in the back cooling chamber, but on the contrary it is heated by the cooling water in the back cooling chamber when temperature of the cooling water in the back cooling chamber becomes higher than that of the gas in the compression chambers by the heat of the discharge gas. The contact area (or heat radiation area) over which the back cooling chamber and the gas cooler are placed in contact with each other through a partition wall tends to be increased with the need to cool the discharge gas in the gas cooler. As the contact area is increased, however, the cooling water in the back cooling chamber tends to be heated by the heat of the discharge gas.